A Practical Method for Improving Delay Performance of Time Slot Allocation in DVB-RCS

In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant effects upon the traffic delay per- formance. This article proposes models to analyze the relationships among frame length, bandwidth assignment (assigned time slot count), time slot location in frame, and traffic delay performance for traffics of constant bit rate (CBR) and variable bit rate (...

Joint slot allocation and dynamic pricing of container sea-rail multimodal transportation

The container sea-rail multimodal transport system faces complex challenges with de- mand uncertainties for joint slot allocation and dynamic pricing. The challenge is formulated as a two-stage optimal model based on revenue management （RM） as actual slots sale of multi-node container sea-rail multimodal transport usually includes contract sale to large shippers and free sale to scattered shippers. First stage in the model utilizes an origin-destination control approach, formulated as a stochastic integer programming equation, to settle long-term slot allocation in the contract market and empty container allocation. Second stage in the model is formulated as a stochastic nonlinear programming equation to solve a multiproduct joint dynamic pricing and inventory control problem for price settling and slot allocation in each period of free market. Considering the random nature of demand, the methods of chance constrained programming and robust optimi- zation are utilized to transform stochastic models into deterministic models. A numerical experiment is presented to verify the availability of models and solving methods. Results of considering uncertain/certain demand are compared, which show that the two-stage optimal strategy integrating slot allocation with dynamic pricing considering random de- mand is revealed to increase the revenue for multimodal transport operators （MTO） while concurrently satisfying shippers＇ demand. Research resulting from this paper will contribute to the theory and practice of container sea-rail multimodal transport revenue management and provide a scientific decision-making tool for MTO.

Hybrid time slot allocation algorithm based on LoRa Internet of things

To improve the efficiency and stability of data transmission in the long-range(LoRa) Internet of things(IoT),a hybrid time slot allocation algorithm is proposed, which implements a priority mechanism with high-priority nodes sending data in fixed time slots and low-priority nodes using the carrier sense multiple access(CSMA) algorithm to compete for shared time slots to transmit data. To improve network efficiency, a gateway is used to adjust the time slot allocation policy according to network status and balance the number of fixed and shared time slots. And more, a retransmission time slot is added to the time slot allocation algorithm, which redesigns the time frame structure, and adopts a retransmission mechanism to improve communication reliability. Simulation and measurement results show that the packet loss rate and transmission delay of the proposed hybrid algorithm are smaller than those of the fixed slot allocation algorithm, making the proposed algorithm more suitable for LoRa IoT.

Dynamic Bandwidth Allocation Scheme for MCNS DOCSIS

This paper gives a method of bandwidth allocation for MCNS DOCSIS, a variable CS/DS allocation algorithm regarding the demands of the data slots is proposed, a numerical example is provided to demonstrate the effectiveness of the proposed method.

Multi-user Symmetric Cooperation Based on Nash Bargaining Solution in Cooperative Relay Networks

This paper presents a symmetric cooperation strategy for cooperative relay networks with multiple users. The multi-user symmetric cooperation model and the relay selection algorithm are proposed. Then, the time slot allocation problem is cast into a bargaining problem, and the optimal time slot allocation solution is obtained by Nash bargaining solution （NBS）. Moreover, we also consider the implementations of the cooperation strategy, i.e., the grouping and admission control algorithm. Simulation results show that users can obtain larger rates under the symmetric cooperation strategy than the non-cooperative case.

Robust Optimization Model for Resource Allocation of Container Shipping Lines

The operating efficiency of container shipping lines depends on proper resource allocation of container shipping.A deterministic model was developed for shipping lines based on the equilibrium principle.The objective was to optimize the resource allocation for container lines considering ship size,container deployment,and slot allocation.The deterministic model was then expanded to a robust optimization model accounting for the uncertain factors,while ship size was treated as the design variable and slot allocation as the control variable.The effectiveness of the proposed model is demonstrated using a pendulum shipping line as an example.The results indicate that infeasible solutions will increase and the model robustness will be enhanced by an increased penalty coefficient and the solution robustness will be enhanced by increasing the preference coefficient.The optimization model simultaneously considers demand uncertainty,model robustness,and risk preference of the decision maker to agree better with actual practices.

Secondary trading of airport slots:Issues and challenges

Most Level 3 airports around the world suffer severe congestion and flight delays.Airlines have to obtain airport slots in order to schedule flights at such airports.The main way for airlines to acquire slots is primary slot allocation,in which a slot coordinator distributes slots to airlines according to certain rules and regulations.Due to excessive demand for slots and restrictions on allocation rules,it is difficult for some airlines to obtain the desired slots in this manner.Another way for airlines to obtain slots is through secondary slot trading,in which slots can be redistributed among airlines without being returned to slot pool.The secondary trading of airport slots has played a positive role in promoting the efficient utilization of slot resources,but systematic studies are insufficient.This paper discusses the reasons for the existence of slot secondary trading,sorts out the main policies and rules governing the mechanism,investigates its impacts on the industry and society,and points out the major problems and challenges.The paper provides a reference for subsequent research and practical application of airport slot secondary trading in the future.